Jean-François Jean-François MoyenMoyen

IgneousIgneous PetrologyPetrology

Lecturer

• Jean-François (Jeff) Moyen

• Contact details: – 021 808 3126– moyen@sun.ac.za– Room 2039 or somewhere else (8:30-17:30)

Class timetable

• Monday 10.00 – 11.00 am (L)

• Tuesday 8.00 – 9.00 am (L)

• Friday 11.00 – 12.00 am (L)

• Wednesday 14.00 – 17.00 pm (P)

• Venues: … depend on the construction work!

Course content

• Tools used to study igneous rocks

• Magmatic processes from melting to final emplacement and cooling

• Some important types of igneous rocks (e.g., mid-ocean ridge basalts, granites, arc magmas, etc.)

And also…

• Scientific approach to geological problems– Observe– Interpret– Conclude

• Writing of scientific texts (structured, rigorous)

• Autonomy– Seek different sources of information– Work from general instructions and device

your own way to the solution

Textbook

Winter, J.D. An introduction to igneous and metamorphic petrology. Prentice Hall, 2002 (also used for Geol 354)

Lecture notes etc.

http://academic.sun.ac.za/geology/undergraduate/modules/geol314_e.htm

Assessment

• Course mark 40%– Pracs (12 x 5 %) = 60%– Field report 20%– Paper presentation 20%

• Exam mark 60%– Open book exam– Based on documents to comment

Practicals

• To be handed in at the latest on the next Monday

• I will try to mark them for the following session (Wednesday)

Field work• One prac will be a field-based exercise

(Sea Point)

• Two days field trip on the West Coast (Cape Columbine) during April break – date to be defined (please think about it)

Paper presentation

• Each student will read, understand and summarize one research paper of importance

• Presentation will consist of– A 1-page handout for the class– A 10 mn oral presentation (+ questions)

• Papers presentations are part of the course – aspects dealt with during presentations will not be repeated

A last word(before we start the real things)

• Please make this course interactive!

• Questions are always welcome and never stupid

• Some parts are more difficult than others (and the first weeks are not the easiest…)

Igneous rocks (magmatic rocks)

• Rocks formed from a magma

• Magma = melt+crystals+bubbles

• More or less obvious

Stromboli (Italy)

Etna (Italy)

Piton de la Fournaise (Réunion, Indian Ocean)

Torres del Paine, S. Chile

Ploumanac’h, France

Cantal extinct volcano, France

« Ignimbrites », Turkey

Bournac volcanic pipe, France

Montserrat, Lesser antilles (1997)

Partially molten rocks

= migmatites

Solidus and Liquidus

Fractional crystallisation

Figure 4-21. Kangâmiut dike swarm in the Søndre Strømfjord region of SE Greenland. From Escher et al. (1976), Geology of Greenland, © The Geological Survey of Denmark and Greenland. 77-95.

Torres del Paine, S. Chile

Ploumanac’h, France

Figure 4-32Figure 4-32.. Developmental sequence Developmental sequence of intrusions composing the Tuolumne of intrusions composing the Tuolumne Intrusive Series (after Bateman and Intrusive Series (after Bateman and Chappell, 1979), Chappell, 1979), Geol. Soc. Amer. Bull.Geol. Soc. Amer. Bull., , 9090, 465-482. , 465-482. a.a. Original intrusion and Original intrusion and solidification of marginal quartz diorite. solidification of marginal quartz diorite. b.b. Surge of magma followed by Surge of magma followed by solidification of Half Dome Granodiorite. solidification of Half Dome Granodiorite. c.c. Second surge of magma followed by Second surge of magma followed by solidification of porphyritic facies of Half solidification of porphyritic facies of Half Dome Granodiorite. Dome Granodiorite. d.d. Third surge of Third surge of magma followed by solidification of magma followed by solidification of Cathedral Peak Granodiorite and final Cathedral Peak Granodiorite and final emplacement of Johnson Granite emplacement of Johnson Granite Porphry. Porphry.

Structures and Field

RelationshipsMagma

Magma

Magma

10 kilometers

N

a b

c d

Marginal quartz diorite Half Dome granodiorite (non-porph)

Half Dome granodiorite (porphyritic) Cathedral Peak granodiorite

Johnson granite porphry

The Peninsula

Range Batholith

(California/Mexico)

Volcanoes feeder complexes

Sub-volcanic Ring DykePiton des Neiges Volcano (extinct), Réunion Isl.

Stromboli (Italy)

From formation to emplacementWhat do we have to study?

• Melting

• Magma transfert

• Magma evolution

• Emplacement (plutons, or volcanoes)

• Final cooling

• … and plate tectonics context

Plate Tectonic - Igneous Genesis

1. Mid-ocean Ridges

2. Intracontinental Rifts

3. Island Arcs

4. Active Continental

Margins

5.5. Back-arc BasinsBack-arc Basins

6.6. Ocean Island BasaltsOcean Island Basalts

7.7. Miscellaneous Intra-Miscellaneous Intra-Continental Continental

ActivityActivity kimberlites, carbonatites, kimberlites, carbonatites,

anorthosites...anorthosites...

Course outline

1. Introduction, background

2. What is a rock made of? Major elements, magmatic series, etc.

3. Melting

4. Magma differenciation and evolution

5. How to identify which process operated? Some geochemistry.

6. Cooling and solidification of magmas

7. Emplacement of plutons

8. Volcanoes

9. Granites

10.Ophiolites and mid-oceanic ridges magmatism

11.Layered igneous complexes

12.Arc magmas

13. Intraplate magmatism

14.Archaean magmatism